A pivot bearing has a radially inner bearing part; a radially outer
bearing part, each of the parts defining a conduit for permiting a
lubricant to pass through, the radially inner bearing part being
supported in a rotary fashion on the radially outer bearing part, a
transmission element that communicates the conduits of the parts to
permit a lubricant to pass through; and a check valve dividing the
conduits into a radially inner conduit system and a radially outer
conduit system.